Those skilled in the art of marine engines are familiar with many different types of steering and trim controls. Those familiar with outboard and stern drive engines typically understand that such engines have trim capabilities associated with the lower unit of the engine. The trim adjusts the pitch attitude of the boat or watercraft while it is moving. Changes in watercraft speed or weight placement usually require trim to be adjusted to keep the boat at a comfortable and efficient pitch attitude. This reduces the work of the engine by reducing the amount of manual control necessary, as well as providing for greater efficiency by keeping the watercraft in the ideal orientation for the water conditions.
Steering and trim execution on outboard and stern drive engines is typically accomplished by two sets of hydraulic cylinders—one or more pairs of hydraulic cylinders for steering, and one or more pairs of hydraulic cylinders for controlling trim. External trim cylinders separate from the steering cylinders is common on Mercury® high performance drives, Volvo® stern drives, and other drives known in the art. Other means of steering contemplate utilizing a lever and an internal steering cylinder, particularly on stern drive engines.
Nowhere in the art, however, is there a combination of external steering and trim execution incorporated into one pair of external hydraulic cylinders. The present application utilizes only two external cylinders, controlled via position sensing and hydraulic valves through a software control strategy. The present invention reduces the trim and stern drive function to two cylinders.
Accordingly, the present invention contemplates a system for combined control of steering and trim of an engine unit generating a propelling force. In one embodiment, the engine unit may be a stern drive unit that includes a gimbal housing and bell housing permitting steering and trim movement. A drive is operatively connected to the bell housing. A drive shaft housing is connected to the drive and encloses a drive shaft. A gear case is connected to the drive shaft housing and encloses gears operatively connected to the drive shaft to rotate a propeller. The system includes a port hydraulic cylinder that extends and retracts, the port cylinder having a first end and a second end, the first end connected to the engine unit at a first port joint, the second end connected to the engine unit at a second port joint. Also included is a starboard hydraulic cylinder that extends and retracts, the starboard cylinder having a first end and a second end, the first end connected to the engine unit at a first starboard joint, the second end connected to the engine unit at a second starboard joint. The first and second starboard joints enable movement of the engine unit vertically and horizontally when the port and starboard cylinders are extended and retracted in order to provide the combined control of steering and trim of the engine unit.
The first port joint and the first starboard joint may be connected to the gimbal housing, while the second port joint and the second starboard joint may be connected to the drive shaft housing. However, points of connection to the engine unit may vary insofar as the use of the two hydraulic cylinders to permit both vertical and horizontal movement of the engine unit to provide control of both steering and trim using two hydraulic cylinders. In this system, when both the port hydraulic cylinder and the starboard hydraulic cylinder are fully extended, the stern drive is lifted into a trailering position, and the steering of the stern drive unit is locked.
The present application further contemplates position sensors connected to each of the port hydraulic cylinder and the starboard hydraulic cylinder that generate position signals. The position sensors may include a steering position sensor and a trim position sensor. They may be located on each hydraulic cylinder. Alternatively, the steering position sensor may be located on a gimbal access of the gimbal ring and a trim position sensor may be located on a trim pivot of the gimbal housing. A steering apparatus generating steering signals and a trim control generating trim signals are also present in the system. The system contemplates an electronic control unit that receives the steering trim and cylinder position signals and sends output signals. The hydraulic manifold has solenoid controlled valves connected to the port hydraulic cylinder and the starboard hydraulic cylinder that receive signals from the electronic control unit to extend and retract the cylinders. More particularly, the solenoid controlled valves receive output signals from the electronic control unit to extend or retract the port hydraulic cylinder and the starboard hydraulic cylinder.
The present application further contemplates a method of controlling steering and trim of an engine unit of a watercraft using two hydraulic cylinders. The method includes the steps of providing a port hydraulic cylinder and a starboard hydraulic cylinder connected to the engine unit, the port and starboard hydraulic cylinders extending and retracting. The method further contemplates maintaining hydraulic cylinder in the starboard hydraulic cylinder at neutral positions for driving the watercraft straight without trim. The method contemplates extending the port hydraulic cylinder and the starboard hydraulic cylinder to raise the engine unit upwardly and trim the watercraft. The method also contemplates the step of extending the port hydraulic cylinder and retracting the starboard hydraulic cylinder to steer the watercraft to starboard. The method further contemplates extending the starboard hydraulic cylinder and retracting the port hydraulic cylinder to steer the watercraft to port. Additionally, the method includes the step of partially extending the port hydraulic cylinder and partially extending the starboard hydraulic cylinder to steer the watercraft to starboard with trim, and also the step of partially extending the starboard cylinder and partially retracting the port hydraulic cylinder to steer the watercraft to port with trim.
The method further contemplates a hydraulic manifold with solenoid valves controlled by electronic signals from an electronic control unit that controls the extension and retraction of the port and starboard hydraulic cylinders. Therein, the method further contemplates the steps of receiving in the electronic control unit a steering input signal from a steering apparatus and sending a steering control signal from the electronic control unit to at least one solenoid valve of the hydraulic manifold to extend or retract a hydraulic cylinder. The method also contemplates receiving in the electronic control unit a trim input signal from a trim control and sending a trim control signal from the electronic control unit to at least one solenoid valve of the hydraulic manifold to extend and retract a hydraulic cylinder. In this embodiment of the present invention, at least one steering control sensor provides a steering position signal to the electronic control unit and at least one trim position sensor provides a trim position signal to the electronic control unit. Thus, an embodiment of the present invention includes a method with the additional steps of receiving in the electronic control unit the steering position signal and the trim position signal, adjusting the steering control signal based on the steering position signal, and adjusting the trim control signal based on the trim position signal.
The method of the present application contemplates that the step of extending the port hydraulic cylinder and the starboard hydraulic cylinder to raise the stern drive unit upwardly and trim the watercraft may further comprise fully extending the port hydraulic cylinder and the starboard hydraulic cylinder to raise the stern drive unit to a trailering position. In that embodiment, full extension of the port hydraulic cylinder and the starboard hydraulic cylinder may lock any steering capability. In the above noted method, the engine unit under control might be an outboard engine unit or a stern drive engine unit.
The present application further contemplates a system for combined control of steering and trim of a marine engine unit, the system including a steering apparatus generating steering signals, a trim control generating trim signals, and an electronic control unit, the electronic control unit receiving trim steering and cylinder position signals and sending output signals. A port hydraulic cylinder that extends and retracts is included in the system, the port cylinder having a first end and a second end, the first end connected to an engine unit at a first port joint, the second end connected to the engine unit at a second port joint. The system also includes a starboard hydraulic cylinder that extends and retracts, the starboard cylinder having a first end and a second end, the first end connected to the engine unit at a first starboard joint, the second end connected to the engine unit at a second starboard joint. Position sensors connected to each of the port hydraulic cylinder and the starboard hydraulic cylinder generate the position signals. A hydraulic manifold having solenoid controlled valves connected to the port hydraulic cylinder and the starboard hydraulic cylinder and operating to extend and retract the cylinders is included within the system. The solenoid valves receive output signals from the electronic control unit to extend or contract the port hydraulic cylinder and the starboard hydraulic cylinder and the first and second port and starboard joints enable movement of the engine unit vertically and horizontally when the port and starboard hydraulic cylinders are extended and retracted. Again, in this embodiment of the invention, the engine unit may be either a stern drive unit or an outboard unit.